index.js

const genCert = require('./genCert');

const fs = require("fs");
const readXlsxFile = require('read-excel-file/node')

// regex expression to validate an email address
const isEmail = (email) => {
    var re = /\S+@\S+\.\S+/;
    return re.test(email);
}

function delay(time) {
    return new Promise(resolve => setTimeout(resolve, time));
}

// reading spreadsheet to obtain the data 
readXlsxFile(fs.createReadStream('./data.xlsx')).then(async (rows) => {
    rows.map(async (row) => {
        // check for validity of email and name
        if (row[0].length > 1 && isEmail(row[1])) {
            // if valid call genCert which will generate the certifiacte and email it
            delay(10000).then(async () => {
                await genCert(row[0], row[1]);
            });
        }
    })
})